Certain cable types where a copper conductor such as a CPC or drain wire might be in contact with an aluminium tape or foil specify that the copper conductors must be tin coated, with no pinholes. Tests are undertaken to check the thickness of tin coating and for the presence or absence of defects.
This test is applied to cables made to:
Test Methods & Equipment
The conductor is carefully removed from the final cable, and immersed in a chemical reagent which seeks out visible copper. In one variant of the test, the copper is dissolved and then analysed. In a more recent variant, the presence of visible copper results in black spots appearing on the conductor, which are examined by eye.